This invention relates to the contactless guidance and suspension of moving vehicles in general and more particularly to an improved electro dynamic system for obtaining suspension and guidance in a vehicle such as a suspension railroad vehicle.
Known systems have been developed for the contactless suspension and guidance of vehicles travelling with high velocity reaching above 300 km/hr. Typically to obtain such suspension and guidance, superconducting magnet loops, preferably installed in the vehicle, are used. The vehicle magnet loops, often referred to as primary conductor loops cooperates with secondary conductor loops or secondary conductor means on the roadbed to provide the necessary suspension and guidance. In electro dynamic systems the secondary conductor means on the vehicle will preferably be rail like bodies of nonmagnetic materials which are sometimes also referred to as rail loops and in which eddy currents will be generated causing a magnetic repulsion force in conjunction with the primary conductor loops to provide the necessary lift or guidance forces for the vehicle. Other systems in which the electromagnetic principle is used and in which the secondary conductors are of a magnetic material utilizing magnetic attraction are also known but have characteristics less desirable than that of the electro dynamic system.
In electromagnetic suspension and guidance systems, two basic configurations have been developed. In what is referred to as a normal flux system and which is disclosed in U.S. Pat. No. 3,589,300, a current carrying primary conductor loop, generally mounted to the bottom portion of the vehicle, moves over an arrangement of metallic secondary conductor loops or rails of nonmagnetic materials. The magnetic field from the primary conductor loop induces eddy currents in the secondary conductor means or rails which eddy currents in turn generate a magnetic field having a direction opposite to the excitation field. As a result the vehicle is repelled from the loops or rails and a lift force produced which is proportional to the product of the rail current and the field component in the direction of the rail body. The eddy current losses and the braking forces generated thereby, on the other hand, are proportional to the square of the field component which runs perpendicular to the dimension of the rail body. In the normal flux system this flux component is relatively large and thus large eddy currents and correspondingly large braking forces are generated along with the required suspension or lifting force.
In what is referred to as a zero flux system and which is described in the publication "Cryogenics," pages 192-204 (1974), it is possible to produce the required lifting force without such large braking forces. In such a system two oppositely polarized magnetic fields of equal strength and facing each other are generated by primary conductor loops attached to the vehicle. The secondary conductor loop is disposed between the two primary conductor loops generating the two magnetic fields. In the plane of symmetry a zone is developed in which the induction in the direction of the thickness of the rail is zero, but the induction over the width of the rail and perpendicular to the direction of motion of the vehicle is twice as large as that obtained with a single coil. When the secondary conductor rail moves away from this region, which is referred to as the zero flux region, the induction in the direction of the thickness of the rail and thus the flux in this region increases while the induction in the direction of the rail perpendicular to the direction of motion in the vehicle remains approximately constant for small excursions. Thus, with relatively small rail currents it is possible to generate the same suspension force as with a normal flux system. The ratio of braking forces to lifting forces is considerably smaller than in a normal flux system. Although the zero flux system keeps braking forces small and results in a good stabilization of the system upward and downward with horizontal support of the vehicle primary conductor loops and the secondary conductor rails, the system always requires two sets of magnet coils to generate the two magnetic fields and these two coils result in large repulsion force on each other. As a result a sufficiently stable mechanical structure is required on the vehicle. This in turn increases the vehicle cost. Furthermore, the rail must be situated between the two coils. This can cause problems in properly supporting the rails.
The normal flux system, on the other hand, requires only a single magnet loop in the vehicle and permits a simple rail design. It has been recognized that a continuous plate which can be supported directly on the road bed will be sufficient for the secondary rail. However, it suffers the above noted disadvantage of large braking forces which then must be made up by the drive system of the vehicle. In German Offenlegungsschrift No. 2,139,506 a suspension and guidance system utilizing electrodynamic principles is disclosed. In the system disclosed therein two superconducting magnet loops fastened to the vehicle and arranged parallel to each other and disposed vertically are used. Between the two loops is a vertical stabilizing loop or secondary conductor rail attached to the road bed and used for generating horizontal lateral guidance forces for the vehicle. Between the two magnet loops is also placed a horizontal secondary conductor rail for generating a suspension force to counteract the force of gravity acting on the vehicle. This additional secondary conductor rail is arranged so as to form a cross with the stabilizing or lateral guidance rail. The system is a combination of two zero flux systems arranged orthogonal to each other and which mutually penetrate each other. To obtain a sufficiently stable attachment of the corresponding combination of the lateral guidance and suspension rails, whose cross sections form a cross perpendicular to the direction of motions of the vehicle, requires particularly strong support members. Also the two rails must be made relatively thick so that they will not be deformed during operation. Thick rails of this nature, however, lead to additional braking losses in the system.
In view of the above noted difficulty the need for an improved suspension and guidance system which lends itself to a simple and stable construction of the supports for stabilizing loops and which has low braking losses becomes evident.